Head & Neck — MCQs

A 27-year-old man comes to the physician because of a 1-day history of right-sided facial weakness and sound intolerance. Three days ago, he hit the right side of his head in a motor vehicle collision. He neither lost consciousness nor sought medical attention. Physical examination shows drooping of the mouth on the right side. Sensation over the face is not impaired. Impedance audiometry shows an absence of the acoustic reflex in the right ear. Which of the following muscles is most likely paralyzed in this patient?

Q42

A 50-year-old man undergoes parathyroidectomy for treatment-resistant hyperparathyroidism. The procedure is complicated by brisk bleeding from the superior thyroid artery near the external branch of the superior laryngeal nerve. To stop the bleeding, the artery is ligated at its origin. Which of the following is most likely the origin of the artery that was injured in this patient?

Q43

A 54-year-old woman comes to the emergency department because of drooping on the left side of her face since that morning. She also reports difficulty closing her eyes and chewing. During the neurologic examination, the physician asks the patient to open her jaw against resistance. Which of the following muscles is most likely activated in this movement?

Q44

A 38-year-old woman undergoes hemithyroidectomy for treatment of localized, well-differentiated papillary thyroid carcinoma. The lesion is removed with clear margins. However, during the surgery, a structure lying directly adjacent to the superior thyroid artery at the upper pole of the thyroid lobe is damaged. This patient is most likely to experience which of the following symptoms?

Head & Neck US Medical PG Practice Questions and MCQs

Question 41: A 27-year-old man comes to the physician because of a 1-day history of right-sided facial weakness and sound intolerance. Three days ago, he hit the right side of his head in a motor vehicle collision. He neither lost consciousness nor sought medical attention. Physical examination shows drooping of the mouth on the right side. Sensation over the face is not impaired. Impedance audiometry shows an absence of the acoustic reflex in the right ear. Which of the following muscles is most likely paralyzed in this patient?

A. Anterior belly of the digastric
B. Stylopharyngeus
C. Cricothyroid
D. Tensor tympani
E. Stylohyoid (Correct Answer)

Explanation: ***Stylohyoid*** - The patient presents with **facial nerve (CN VII) injury** following head trauma, evidenced by **facial weakness** and **hyperacusis** (sound intolerance). - The **absent acoustic reflex** indicates paralysis of the **stapedius muscle** (the primary muscle responsible for the acoustic reflex and sound dampening). - Among the options provided, **stylohyoid** is the only muscle innervated by the **facial nerve (CN VII)**, making it the correct answer in this context. - The stylohyoid is innervated by the **nerve to stylohyoid**, a branch of CN VII. *Anterior belly of the digastric* - The **anterior belly of the digastric** is innervated by the **mylohyoid nerve**, a branch of the **trigeminal nerve (CN V3)**. - This would not be affected in facial nerve injury. *Stylopharyngeus* - The **stylopharyngeus muscle** is innervated by the **glossopharyngeal nerve (CN IX)**. - Damage would cause **dysphagia** and **loss of taste** on the posterior third of the tongue, not facial weakness or hyperacusis. *Cricothyroid* - The **cricothyroid muscle** is innervated by the **external branch of the superior laryngeal nerve** (from **vagus nerve, CN X**). - Its paralysis causes **voice changes** and difficulty with high-pitched phonation, not facial nerve symptoms. *Tensor tympani* - The **tensor tympani muscle** is innervated by the **nerve to tensor tympani**, a branch of the **trigeminal nerve (V3)**. - Although it dampens sound, it would not be affected in facial nerve injury; the **stapedius muscle** (CN VII) is responsible for the acoustic reflex and hyperacusis when paralyzed.

Question 42: A 50-year-old man undergoes parathyroidectomy for treatment-resistant hyperparathyroidism. The procedure is complicated by brisk bleeding from the superior thyroid artery near the external branch of the superior laryngeal nerve. To stop the bleeding, the artery is ligated at its origin. Which of the following is most likely the origin of the artery that was injured in this patient?

A. Thyrocervical trunk
B. Ascending pharyngeal artery
C. Internal carotid artery
D. Subclavian artery
E. External carotid artery (Correct Answer)

Explanation: ***External carotid artery*** - The **superior thyroid artery** is the first branch to arise from the **external carotid artery** in the neck. - Ligation of this artery at its origin is a common surgical maneuver to control bleeding during thyroid or parathyroid surgery. *Thyrocervical trunk* - The **thyrocervical trunk** is a branch of the **subclavian artery** and gives rise to the inferior thyroid artery, not the superior thyroid artery. - Injury to the superior thyroid artery would not necessitate ligation of a vessel originating from the thyrocervical trunk. *Ascending pharyngeal artery* - The **ascending pharyngeal artery** is a small artery that branches from the **external carotid artery** but supplies the pharynx, not the thyroid gland. - It is not typically implicated in bleeding during parathyroidectomy or in relation to the superior laryngeal nerve. *Internal carotid artery* - The **internal carotid artery** primarily supplies the brain and does not have branches in the neck that supply the thyroid or parathyroid glands. - It arises from the common carotid artery but does not give off the superior thyroid artery. *Subclavian artery* - The **subclavian artery** gives rise to the **thyrocervical trunk**, which then supplies the inferior thyroid artery, but not directly the superior thyroid artery. - The superior thyroid artery originates higher up from the external carotid artery.

Question 43: A 54-year-old woman comes to the emergency department because of drooping on the left side of her face since that morning. She also reports difficulty closing her eyes and chewing. During the neurologic examination, the physician asks the patient to open her jaw against resistance. Which of the following muscles is most likely activated in this movement?

A. Hyoglossus
B. Masseter
C. Orbicularis oris
D. Buccinator
E. Lateral pterygoid (Correct Answer)

Explanation: ***Lateral pterygoid*** - The **lateral pterygoid muscle** is the primary muscle responsible for **opening the jaw (depressing the mandible)** and protruding it. - When opening the jaw against resistance, this muscle would be actively engaged and contracting to overcome the opposing force. *Hyoglossus* - The **hyoglossus muscle** is a muscle of the tongue, primarily involved in **depressing and retracting the tongue**. - It does not play a role in the movement of the jaw itself. *Masseter* - The **masseter muscle** is one of the primary muscles of **mastication**, responsible for **closing the jaw (elevating the mandible)** and clenching the teeth. - It would be active during jaw closure against resistance, not during jaw opening. *Orbicularis oris* - The **orbicularis oris muscle** surrounds the mouth and is responsible for **pursing the lips**, closing the mouth, and other facial expressions related to the mouth. - It is not involved in the movement of the jaw itself. *Buccinator* - The **buccinator muscle** is a facial muscle that forms the wall of the cheek and is involved in **compressing the cheek** (e.g., during blowing or sucking) and keeping food pocketed during chewing. - It does not directly participate in the opening or closing of the jaw joint.

Question 44: A 38-year-old woman undergoes hemithyroidectomy for treatment of localized, well-differentiated papillary thyroid carcinoma. The lesion is removed with clear margins. However, during the surgery, a structure lying directly adjacent to the superior thyroid artery at the upper pole of the thyroid lobe is damaged. This patient is most likely to experience which of the following symptoms?

A. Shortness of breath
B. Weakness of shoulder shrug
C. Voice pitch limitation (Correct Answer)
D. Difficulty swallowing
E. Ineffective cough

Explanation: ***Voice pitch limitation*** - Damage to the structure directly adjacent to the **superior thyroid artery** at the upper pole of the thyroid likely involves the **external branch of the superior laryngeal nerve (EBSLN)**. - This nerve innervates the **cricothyroid muscle**, which is responsible for **tensing the vocal cords** and controlling **voice pitch**. - Injury results in inability to change pitch, voice fatigue during prolonged speaking, and reduced vocal range. *Shortness of breath* - While damage to other nerves like the **recurrent laryngeal nerve** could cause vocal cord paralysis and potentially lead to airway compromise, this is less directly associated with the superior thyroid artery. - Shortness of breath is not the specific consequence of EBSLN injury near the superior thyroid artery. *Weakness of shoulder shrug* - Weakness of shoulder shrug is associated with damage to the **spinal accessory nerve (cranial nerve XI)**, which innervates the **trapezius muscle**. - This nerve is anatomically distinct from structures near the superior thyroid artery at the upper pole of the thyroid. *Difficulty swallowing* - Difficulty swallowing (dysphagia) can result from damage to the **vagus nerve (cranial nerve X)** or its pharyngeal branches, but it is not the direct consequence of injury near the superior thyroid artery. - Damage to the EBSLN primarily affects voice pitch and quality, not swallowing. *Ineffective cough* - An ineffective cough results from paralysis of the vocal cords (preventing glottic closure) or weakness of respiratory muscles, typically from **recurrent laryngeal nerve** damage or phrenic nerve injury. - EBSLN damage primarily affects voice pitch and does not significantly impair cough effectiveness.

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Head & Neck — MCQs

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